An 18-year-old man with a 12-year history of type 1 diabetes mellitus comes to the physician for a follow-up examination. medications include 25 u of nph insulin and 10 u of regular insulin in the morning and 10 u of nph insulin and 10 u of regular insulin before dinner. his hemoglobin a1c was 14.5% 12 weeks ago. his current pulse is 80/min, respirations are 20/min, and blood pressure is 145/95 mm hg. examination shows scattered retinal microaneurysms bilaterally. the remainder of the examination shows no other abnormalities. laboratory studies show: hemoglobin a1c 13%serum na+ 130 meq/lk+ 3.2 meq/lcl− 101 meq/lhco3− 23 meq/lglucose 325 mg/dlcreatinine 1.5 mg/dlcholesterol 350 mg/dlurineblood negativeglucose 4+protein 1+ketones negativewhich of the following is the most likely renal diagnosis? (a) cholesterol renal emboli(b) diabetic nephropathy(c) hypertensive glomerulosclerosis(d) hypokalemic nephropathy(e) sodium-losing nephropathy